FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 89 



across the cerebellar region. The postorbital constriction is very 

 slight and postorbital processes are lacking. 



The complete, sigmoid zj^goma arises nearly at the middle of the 

 palatal region, opposite P^~*. 



The most striking characteristic of general outline is the extremely 

 posterior position of the glenoid surfaces, wliich extend almost to the 

 plane of the occiput, so that the basicranial region is remarkabl}'^ 

 short and wide. There are no pre- or post-glenoid and probably no 

 paroccipital processes. The vnde occipital condyle has a cochleate 

 surface, its ventral exposure larger than the posterior. 



The nasals, which are unfused, are broad, stout bones. They are 

 slightly constricted near their middle portion, and expanded posteri- 

 orly. The nasofrontal suture, slightly curved so that the frontals are 

 inserted into a broad and very shallow notch between the nasals, 

 almost exactly touches at its most posterior point a line joining the 

 most anterior margins of the two orbits. There are several small 

 foramina in the nasals, the most prominent a pair, one near the middle 

 of the posterior half of each nasal. 



The premaxillae show no characters of interest. Their posterior 

 facial sutures cannot be made out, or the extent of their palatal 

 expansion, although they meet at the midhne as far back as the anterior 

 end of I^. 



The maxilla is a relatively very large bone. It has a small frontal 

 contact above the anterior rim of the orbit. *° It forms the whole 

 anterior root of the zygoma and apparently at least half of the zygoma 

 itself. I can detect no jugal. It may have existed as a slender bone 

 above the zygomatic portion of the maxilla, as shown in Broom's 

 restoration, but this is purely hypothetical. No. 9710 has the zygoma 

 nearly complete, although fractured and dislocated, and in it no jugal 

 is visible, so that it is quite possible that this bone was wholly lacking 

 or fused with the maxilla. On the palate, the maxiUae form a strong 

 transverse bridge, principally between P^~^ of opposite sides. Anterior 

 to this in the midline they form a pointed process between the anterior 

 palatal foramina, which are very large and lie between but in greater 

 part posterior to the second incisors. Posterior to the transverse 

 palatal bridge of the maxillae is a slender median bar between the 

 vacuities, but whether this is formed by the maxillae, palatines, or 

 both cannot be made out. Broom (1914, p. 123) has mentioned that 

 "the front part of the maxilla is curiously excavated as if it retained a 

 large nasal floor cartilage." The excavation opens at the postero- 

 lateral side of the anterior palatal foramen and is cut off from the 

 nasal passage proper by a flange of bone from the maxilla. As shown 



'" Broom (1914) shows maxilla and frontal separated by a small lacrimal, but this is hypothetical (dotted 

 lines on his drawing). In fact, no lacrimal is distinguishable, and there does appear to be a definitely visible 

 frontomaxillary contact on the right side. This region is known in several multituberculates, and none 

 shows a lacrimal, at least outside the orbit. Probably this bone is lacking or irtracrbital in this order. 



